Learning to Tig Weld

[Salty]

So, I bought a PT250EX set it up and started to run beads, I got bored and started to weld outside corners and butt joints. Thought I was making progress until I tried to make a T weld, WOW this is a real challenge for me. Please feel free to make any suggestions on what I should do and how I should set my welder. This is 1/8th inch aluminum. Thank you in advance for your suggestions.

[geezer]

Don't see much of a problem on your T weld other than you start to speed up the rod dip's as though you are getting tired of wating for it to happen, Other than that you start out just fine and need some more patience, everything else looks good to me, your mention of "getting bored" could be the key to it all.

[Nikola Tesla]

Hello,

I was curious if anybody had any reading material or online material for learning they would suggest? I'm still in the tinkering stages with my 250ex. Ive tinkered with some stainless and various grades of steel. I find that I am doing more grinding, sanding and cleaning then anything else. I love my little grinding wheel set up. A cutter, a wire wheel and a grinder. All small little handhelds to get the job done while Im still focussed on the weld.

[jakeru]

Looks like you're getting this down. Try reducing your current so you have better control with your footpedal on the light current end. It will help when you need to taper the heat way back near those edges. Keep a real tight arc to maintain precise heat control especially when approaching an edge too.

How do the back sides look?

Try welding some flat coupons and bend them using in a vice until they fail, then inspect the fracture to see how much penetration you are getting.

[Salty]

I think on this T weld I was not so good with the foot pedal so I was trying to keep the metal from burning through by cooling the puddle with the filler rod. The T welding is not boring at all it can be pretty exciting

[Salty]

Thanks for the advice, on this 1/8" Aluminum about where should I be with my amp setting when attempting a T weld? Sometimes the arc wanders around and does not go where I want the heat to go what causes that to happen?

[performance]

Salty,
Basic electricity theory says that electricity tries to find the closest route to ground with the least resistance to flow(generally). Your minute variations in your technique can change the proximity of the arc from the sides of the joint, causing it to bounce. Dirty metal will do it as well. Having a ball on the end or too large of a tungsten for the amps will do it as well. To reduce this fluctuation: 1) grind your tungsten to a point, and keep it domed, not balled. 2) Increase the AC frequency. This will pinpoint the arc and make it more stable. 3) Get some crackers and eat them about 30 minutes before you start welding.

[Rugar]

3) Get some crackers and eat them about 30 minutes before you start welding.

Any particular brand work better then others? Or will just the cheap generic crackers work? I usually just stuff my pockets with the ones on the tables around me when ever I go to restaurants.

[performance]

Lance Smokehouse cheddar work for me.

[Salty]

There is some good reading at the Miller site, go to resources and then to improving your skills. Also you can rent the Ron Covell vidios at smart flix for about 10 bucks.

[Salty]

Thanks for the tips just talking about food makes me hungry

[Wrenchtamer]

Yeah I totally don't get the cracker thing and it's driving me mad.

[angular]

Smoked cheddar and crackers does sound really good about now. It's officially beer-thirty where I'm at (left coast). Cheers.

[jakeru]

Thanks for the advice, on this 1/8" Aluminum about where should I be with my amp setting when attempting a T weld? Sometimes the arc wanders around and does not go where I want the heat to go what causes that to happen?

When the arc wanders all around on me, if its not caused by contamination, it is usually fixed by switching to a smaller tungsten diameter. If you don't run enough current on a given size tungsten, the arc will be "unstable" and can kind of wander all around with a mind of its own. You will achieve a more stable, "directional" arc when you use enough current for the tungsten size.

So, you might try going down a size on your tungsten. Definitely make sure its a clean tungsten too. If you let aluminum "wick" up around your hot tungsten, grind off a good portion of the tungsten. It seems the aluminum can soak up inside the tungsten so just grinding off the visible aluminum is not necessarily enough. If the tip of your tunsten is not melting, it's probably not too small. Grind a small flat on the tip to increase its current carrying capability.

Holding a tighter arc can also be helpful to direct the heat of the tungsten better.

If you prevent the work from heating up as much when you are welding near the edge, you won't need to taper off the current so much and maybe can get away welding the ends without going to the larger tungsten. Easiest way to do this is by tack welding the edges first, and get it out of the way before the part has had a chance to heat up. Its especially important when welding a small coupon like you are doing. Increasing travel speed and welding "hotter and faster" may be helpful also. (But you'll have to coordinate your torch and filler movements more quickly.)

You might try increasing your A/C frequency as well, which makes the arc more directional. (Similar effect can also be accomplished when DC welding or on AC welding machines as well, by adding in some high frequency pulsing, like 300Hz) But, definitely experiment with the other methods especially tungsten size selection, grinding, maintenance, and arc distance when welding.

Edit: here is a chart for selecting tungsten diameter based on welding current. (Refer to the "thoriated" column if you are using lanthanted or ceriated.)
http://www.ckworldwide.com/tech-3.pdf

So interpreting the chart, if you are AC welding with a 3/32" (thoriated/ceriated/lanthanted) tungsten, you should be using a current range of 140-235 amps. That's probably a bit too big of a tungsten for this small coupon, which will heat up quickly and probably have you tapering the amps down low if you are not traveling really, really fast.

Whereas if you used 1/16" tungsten (thoriated/ceriated/lanthanted), you are good for 70-150 amps. That seems like a better operating range for the 1/8" coupons you are welding.

[angular]

Good stuff, Jake. I would just add that in this document from CK on page 4 (5th page of the PDF) it shows much wider current ranges for various size tungsten electrodes.

http://www.ckworldwide.com/technical_specs.pdf

[performance]

Yeah I totally don't get the cracker thing and it's driving me mad.

It works best around 10,2 and 4, along with a little hydration therapy from a diet doctor pepper.

[Salty]

Thanks jakeru, I think you explained it perfectly. I was using a 3/32, 2% lanthanated at about 90-100 amps I will work with the 1/16 sharpened like you described.